CN201294387Y - Energy-saving capacitance compensation switching controller - Google Patents

Abstract

The utility model discloses an energy-saving capacitor compensation switching controller, which comprises a control input circuit, a working state indication circuit, a 485 interface circuit, a temperature detection circuit, a microprocessor circuit, a thyristor drive circuit, a relay drive circuit, a SCR, relay, zero-crossing acquisition circuit and regulated power supply circuit, the thyristor and the relay are connected in parallel, and the relay adopts a magnetic latching relay. When switching, the zero-crossing point of the AC voltage is first detected by the zero-crossing acquisition circuit, and then when the voltage crosses zero In an instant, the silicon controlled rectifier is first triggered at zero crossing, and then the magnetic latching relay is turned on with a delay. When cutting out, the magnetic latching relay is first disconnected, and the silicon controlled rectifier is disconnected at zero crossing delay, so as to realize the current zero crossing Cut off, due to the use of magnetic latching relays, the state of the relays can be maintained, no need to provide working power. It has the characteristics of energy saving. At the same time, the temperature detection circuit is used to detect the surface temperature of the capacitor in real time. When the temperature exceeds the limit, an alarm will be issued to extend the service life of the capacitor. The role of the 485 interface circuit can be left at the same time remote control.

Description

Energy-saving capacitor compensation switching controller

technical field

The utility model relates to an energy-saving capacitor compensation switching controller capable of automatically switching capacitors.

Background technique

In industrial and enterprise power supply systems, since the vast majority of electrical equipment are inductive loads, these electrical equipment use a considerable amount of reactive power in addition to active power from the power supply system during operation. Some production equipment (such as rolling mills, electric arc furnaces, etc.) often have reactive impact loads during the production process, and this impact load may increase by 5 to 6 times compared to the normal reactive power. It is known from circuit theory that the increase of reactive power reduces the power factor of the power supply system. The reduction of power factor will lead to: the increase of power loss in the grid loop; the increase of voltage loss in the grid loop; the decrease of the power supply capacity of the power supply equipment and the increase of the cost of electric energy. In order to encourage enterprises to improve their power factors, the People's Republic of China stipulates an additional reward and punishment system that adjusts the amount of electricity charges collected according to the level of the power factor of enterprises when collecting electricity fees under the two-part electricity price system. According to this system, for enterprises whose monthly average power factor is higher than the specified value, the electricity fee can be reduced correspondingly according to the excess, and when the power factor is lower than the specified value, the electricity fee will be increased. It is clearly stipulated in the "National Power Supply and Utilization Rules" that when the power factor is lower than 0.7, the power bureau may not provide power supply. Therefore, enterprises must consider compensation no matter whether they start from saving electricity costs, improving power supply quality or improving the power supply capacity of power supply equipment. The measure of reactive power, and the compensation of reactive power is usually realized by connecting capacitors in parallel in the grid.

However, the load in the actual power grid is constantly changing, and the power factor is also changing at any time. In order to adapt to the changing power factor of the power grid, it is required to use multiple groups of capacitors to switch in groups to achieve the purpose of dynamically compensating the power factor of the power grid. The switching of capacitors mainly adopts thyristor switching or AC contactor switching. Due to the large inrush current during capacitor switching, although it can be switched at zero crossing, the thyristor requires a large heat dissipation area and a large volume. , while the AC contactor is used for switching, the volume is small, but it cannot be guaranteed to switch at the zero crossing point, the contacts are easy to sinter, and the AC contactor needs to be powered all the time, resulting in energy waste. At the same time, the existing capacitance compensation controller does not reserve 485 The interface and capacitor temperature measurement circuit cannot monitor the temperature of switched capacitors in real time, resulting in damage to the capacitors in the compensation cabinet due to excessive temperature.

Utility model content

The technical problem to be solved by the utility model is to provide a capacitor that can be switched at the zero crossing point, so that there is no inrush current when the switch is switched, the contacts are not sintered, the volume is small, the energy consumption is small, no transient state and harmonics are introduced, and it can Monitor the temperature of the capacitor in real time.

In order to solve the above technical problems, the utility model provides an energy-saving capacitor compensation switching controller, including a control input circuit, a working state indication circuit, a 485 interface circuit, a temperature detection circuit, a microprocessor circuit, and a thyristor drive circuit , Relay drive circuit, SCR, relay, zero-crossing acquisition circuit and regulated power supply circuit.

The output end of the control input circuit is connected to the I/O port of the microprocessing circuit, the input end of the working state indication circuit is connected to the I/O port of the microprocessing circuit; the signal output end of the temperature detection circuit is connected to the A/D port of the microprocessing circuit The 485 interface circuit is connected to the serial port of the microprocessing circuit; the input end of the thyristor drive circuit is connected to the I/O port of the microprocessing circuit, and the output end of the thyristor drive circuit is connected to the trigger end of the thyristor; The input end of the relay driving circuit is connected to the I/O port of the microprocessing circuit, the output end of the relay driving circuit is connected to one end of the coil of the relay, and the other end of the coil of the relay is connected to the positive polarity end of the power supply; the input and output ends of the thyristor The two contacts of the relay are connected in parallel to the input of the zero-crossing acquisition circuit, and the output of the zero-crossing acquisition circuit is connected to the I/O port of the microprocessing circuit; the regulated power supply circuit is connected to the microprocessing circuit and the relay driver respectively. Circuit connection to provide power to it. The relay adopts magnetic latching relay. The thyristor driving circuit is driven by a pulse transformer. The zero-crossing acquisition circuit adopts a photoelectric coupling device to realize the acquisition of the zero-crossing point of the AC voltage.

The zero-crossing acquisition circuit converts the sine wave signal at both ends of the switch into a square wave signal through the optocoupler circuit, and sends it to the microprocessor circuit for zero-crossing detection, so that when the controller receives the switch closing control command, it closes at the zero-crossing point, and the optocoupler isolates The circuit also has the function of strong current and weak current isolation, and the circuit also has the detection of phase loss information. When the switch of this road is out of phase, there is no signal sent from this road at this time, so it can be judged whether the road is faulty or not according to whether there is a signal sent out. Mutually. The resistance-capacitance protection circuit of the thyristor is connected in parallel at both ends of the bidirectional thyristor to protect the thyristor, and at the same time as the acquisition of the switching AC voltage waveform signal, the thyristor mainly plays an auxiliary role, because the thyristor responds The speed is fast, but the response speed of the relay is slow, so when the switch is closed, the thyristor is closed first, and then the relay is closed within tens of milliseconds or a few seconds, so that the switch can be switched at the zero crossing point, and the thyristor is closed after the switch is closed. When the terminal voltage is zero, the thyristor is automatically turned off.

The utility model has positive effects: (1) In the energy-saving capacitor compensation switching controller of the utility model, the relay selects a magnetic latching relay, adopts a thyristor and a relay in parallel, and closes the thyristor first when closing, and then closes The relay and the controller can automatically track the zero point, which can ensure that the switch is switched at the zero point, the zero point switching switch will not generate transients and harmonics, and the contacts will not be sintered. Since the magnetic latching relay does not need to maintain the voltage after working, Therefore, the use of magnetic latching relays has the purpose of saving energy. (2) The energy-saving capacitance compensation switching controller of the utility model has the function of measuring the surface temperature of the capacitor. When the capacitor is overheated, it will alarm, or when the capacitor is overheated, the capacitor will be cut off from the circuit to prolong the service life of the capacitor.

Description of drawings

Fig. 1 is the general structural diagram of embodiment 1.

FIG. 2 is a schematic diagram of the capacitor switching control in Embodiment 1. FIG.

Detailed ways

As shown in Figure 1 and Figure 2, the energy-saving capacitor compensation switching controller of this embodiment includes a control input circuit, a working status indicator circuit, a 485 interface circuit, a temperature detection circuit, a microprocessor circuit, and a thyristor drive circuit , Relay drive circuit, SCR, relay, zero-crossing acquisition circuit and regulated power supply circuit.

The thyristor trigger circuit in Figure 2 is realized by a pulse transformer T, and the IN frequency signal from the oscillator circuit generates a pulse signal through the pulse transformer T to control the bidirectional thyristor circuit. D1 in Figure 2 is a bidirectional thyristor. The relay drive circuit is mainly used to control the relay. In Figure 2, K0 is the relay, and R1 and C1 in Figure 2 are the resistance-capacitance protection circuit of the thyristor, which are connected in parallel at both ends of the triac D1 for protection. The thyristor is also used as the acquisition function of the switching AC voltage waveform signal. The thyristor and the relay are connected in parallel, and the thyristor mainly plays an auxiliary role. Since the thyristor responds quickly and the relay responds slowly, When the switch is closed, first close the thyristor and then close the relay within tens of milliseconds or a few seconds, so as to ensure that the switch is switched at the zero crossing point. After the switch is closed, the voltage at both ends of the thyristor is zero. At this time, the thyristor Automatic shutdown. In Figure 2, IC1 is an optocoupler device used for zero-crossing collection. Its main principle is to convert the sine wave signal into a square wave signal and send it to the single-chip microcomputer, and the optocoupler device also plays an isolation role. The regulated power supply circuit mainly provides power to the controller. The working state indication circuit is used to indicate the working state of the circuit, and adopts light-emitting diodes. The control input circuit is composed of a photoelectric isolation circuit and is mainly used to receive external control commands. When a switch action (close or open) is required, the external circuit sends a pulse signal to the controller, which is sent to the microprocessor circuit through photoelectric isolation. For control, R0, R2, and R3 in Figure 2 are current-limiting resistors, D2 in Figure 2 is a rectifier diode, C0 in Figure 2 is an external compensation capacitor, and E3 and E4 in Figure 2 are two connected to the power supply. Terminal block, V _CC in Figure 2 is the DC power supply for optocoupler waveform conversion.

The temperature acquisition in the temperature acquisition circuit can be done by digital temperature sensors AD590, LM92, or by a thermistor (such as 10KΩ, 35KΩ). In this embodiment, a 10KΩ thermistor is used.

Microprocessor circuit selects PIC, NSP430, 51 or AVR series etc. for use, adopts AVR series ATMEGA16 single-chip microcomputer in the present embodiment.

The voltage-stabilizing power supply circuit is composed of a step-down circuit, a rectifier circuit, a voltage-stabilizing circuit and a filter circuit. The step-down circuit in this embodiment adopts a small-power transformer to step down, and the transformation ratio is: 380VAC/12VAC; the rectification circuit adopts a rectifier bridge; The voltage circuit uses a three-terminal voltage regulator module, LM7805 is used in this embodiment; the filter circuit uses capacitor filtering.

The triac is selected as the triac, and the BAT40 triac is used in this embodiment.

Claims (4)

1, energy-saving capacitance compensation switching controller, it is characterized in that, comprise control input circuit (1), operating state indicating circuit (2), 485 interface circuits (3), temperature sensing circuit (4), microcontroller circuit (5), controllable silicon drive circuit (6), relay drive circuit (7), controllable silicon (8), relay (9), zero crossing Acquisition Circuit (10) and voltage-stabilized power supply circuit (11); The output of control input circuit (1) is connected with the I/O mouth of microcontroller circuit (5), and the input of operating state indicating circuit (2) is connected with the I/O mouth of microcontroller circuit (5); The signal output part of temperature sensing circuit (4) is connected with the A/D mouth of microcontroller circuit (5); 485 interface circuits (3) are connected with the serial ports of microcontroller circuit (5); The input of controllable silicon drive circuit (6) is connected with the I/O mouth of microcontroller circuit (5), and the output of controllable silicon drive circuit (6) is connected with the trigger end of controllable silicon (8); The input of relay drive circuit (7) is connected with the I/O mouth of microcontroller circuit (5), and the output of relay drive circuit (7) is connected the positive ends of another termination power of coil of relay (9) with coil one end of relay (9); Be connected to the input of zero crossing Acquisition Circuit (10) after two tip side parallel connections of the input and output side of controllable silicon (8) and relay (9), the output of zero crossing Acquisition Circuit (10) is connected with the I/O mouth of microcontroller circuit (5); Voltage-stabilized power supply circuit (11) is connected with relay drive circuit (7) with microcontroller circuit (5) respectively, for it provides power supply.

2, energy-saving capacitance compensation switching controller as claimed in claim 1 is characterized in that, relay (9) adopts magnetic latching relay.

3, energy-saving capacitance compensation switching controller as claimed in claim 1 is characterized in that, controllable silicon drive circuit (6) adopts pulse transformer to drive.

4, energy-saving capacitance compensation switching controller as claimed in claim 1 is characterized in that, zero crossing Acquisition Circuit (10) adopts photoelectric coupled device to realize the collection of alternating voltage zero-crossing point.

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